International Telephone and Telegraph Corporation

Peter D Steensma

Charles K Kao

Robert H Haussmann

Thomas E Finley

Robert W Smid

Anton J Polcer

Murray Weinberg

The asynchronous integrated voice and data communication system includes a continuously variable slope delta encoder and a continuously variable slope delta decoder to convert voice signals to coded signals and vice versa. A packetizer and a depacketizer are employed with each data and voice user to enable each of the plurality of data and voice users to have random access to a fiber optic transmission medium enabling each of the plurality of data and voice users to receive transmissions from all others of the plurality of users. A microcomputer is coupled to each of the voice and data users and the associated packetizer and depacketizer to enable any one of the plurality of data and voice users to establish communication with any other selected one of the plurality of data and voice users.

Asynchronous integrated voice and data communication system

The frequency synthesizer to generate a selected, adjustable discrete frequency output signal comprises a pair of acoustic means, a circuit to excite one of the pair of acoustic means with pulses having a given repetition frequency and to excite the other of the pair of acoustic means by the pulses after being delayed a given variable amount, and a frequency mixer coupled to each of the pair of acoustic menas to provide the selected discrete frequency output signal. Several embodiments of the acoustic means are disclosed.

Frequency synthesizer

A fault locating arrangement for a two-way repeatered transmission link comprising a source in one of the terminals to transmit a unique signal in a first transmission direction from the one of the terminals to the other of the terminals through the repeaters, and a first unique signal detector, a second unique signal detector and logic circuitry disposed in at least the other of the terminals and each of the repeaters. The first unique signal detector is coupled to the first transmission direction, the second unique signal detector is coupled to the opposite transmission direction and the logic circuitry is coupled to the first and second unique signal detectors such that, when the unique signal traveling in the first transmission direction is detected, a loop connection is established for the unique signal from the first transmission direction to the opposite transmission direction and the unique signal is transmitted in the first transmission direction beyond an associated one of the repeaters. The logic circuitry breaks the loop connection when the unique signal is detected traveling in the opposite transmission direction and maintains the loop connection when the unique signal is not traveling in the opposite transmission direction. A phase comparator disposed in the one of the terminals responds to the unique signal transmitted in the first transmission direction and received from the opposite transmission direction to provide an indication of the location of a fault in the transmission link.

Fault locating arrangement for a two-way repeatered transmission link

An optical fiber having a center core and an outer core coaxial of the center core is coupled in a loop to a control station and a plurality of equally spaced users. The fiber propagates data time sequentially between the plurality of users on the center core in a given direction around the loop. A source of masking signal disposed in the control station is propagated on the outer core in a direction around the loop opposite to the given direction to prevent intercepting data on the fiber. The masking signal is turned off at a given time for a predetermined length of time to provide a window in the masking signal which arrives at each of the plurality of users in time sequence coincident with the data intended for each of the plurality of users to enable each of the plurality of users to recover the data intended therefore.

Multiuser protected optical data bus distribution systems

The intelligence on an optical communication system is made secure by launching an intelligence modulated optical beam into the input end of an optical waveguide at a small angle with respect to the axis of the waveguide and launching a masking signal modulated optical beam into the input end of the waveguide at a high angle with respect to the axis of the waveguide. At the output end of the waveguide only the intelligence modulated optical beam is transmitted to an optical detector with the masking signal modulated optical beam being blocked from the detector. This prevents an intruder from separating the intelligence signal from the masking signal when observing the waveguide radially.

Method and apparatus to provide a secure optical communication system

An intelligence modulated optical beam is injected into an optical waveguide through a beam splitter. At the output end of the optical waveguide the optical beam has a portion thereof transmitter through a partial reflector to a detector or receiver with a portion of the optical beam at the output of the waveguide being reflected back into the waveguide with the reflected beam being reflected by the beam splitter to a correlator. A replica of the intelligence of the injected optical beam delayed an amount equal to the round trip transit time of the optical beam is supplied as the other input of the correlator. The delayed replica of the intelligence of the optical beam and reflected optical beam are correlated to produce an output from the correlator proportional to the attenuation or intensity of the reflected beam. When the output of the correlator falls below a given value, an alarm is actuated indicating that an intruder has intercepted intelligence of the optical beam transmitted through the waveguide.

Intruder alarm arrangement for an optical communication system

An amplitude modulation modulated acoustic wave is coupled to a selected region along the length of an optical fiber waveguide transmitting an optical beam to modulate at least one transmission characteristic of the waveguide in the selected region by the amplitude modulation of the modulated acoustic wave to impart the amplitude modulation of the modulated acoustic wave to the optical beam.

Optical amplitude modulation modulator

The dispersion effects in an optical fiber transmission line are equalized by producing a predetermined delay characteristic for each wavelength of an optical beam having a finite bandwidth which is the inverse of a given delay characteristic for each optical wavelength propagated through the transmission line. This is accomplished by launching shorter wavelength components of the optical beam at low angles with respect to the axis of the transmission line into the transmission line and launching longer wavelength components at high angles with respect to the axis of the transmission line into the transmission line. Two arrangements are disclosed to accomplish the above-mentioned launching technique. One arrangement includes a time of flight dependent annularly ruled transmission grating and the other arrangement includes passing a time of flight dependent moving acoustic wave through the optical beam.

Method and arrangements for dispersion equalization of optical fiber

The communication system includes a holographic system to provide a plurality of spatially multiplexed optical beams each modulated by a different one of a plurality of binary intelligence signals. The plurality of modulated spatially multiplexed optical beams are coherently transmitted on an optical waveguide to a hologram and an array of photosensors to recover each of the intelligence signals. The waveguide may be an optical fiber of the parabolic index type to coherently transmit all of the plurality of modulated spatially multiplexed optical beams, or a plurality of single mode step index optical fibers each coherently transmitting a different one of the plurality of modulated spatially multiplexed optical beams.

Secure optical multiplex communication system

A matrix of electrical to light converting diodes are each coupled to different ones of a plurality of incoming telephone lines. These diodes emit light at all times and have their light intensity modulated by intelligence when intelligence is present on their associated one of the incoming telephone lines. A corresponding matrix of optical to electrical converting diodes are each coupled to a different one of a plurality of outgoing telephone lines. A holograpic plate having a corresponding matrix of stored holograms is positioned between the input and output diode matrixes. Each of the stored holograms is uniquely related to a different one of the outgoing telephone lines. An optical coupling device responsive to incoming telephone dial signals is disposed between the first mentioned diode matrix and the hologram. In response to the dial signal, the optical coupling device spatially phase modulates the optical signals from the first mentioned diode matrix transverse to the direction of propagation of these optical signals. The resultant light beams at the output of the optical coupling device has a unique pattern of spatial phase modulation for each of the possible dial signals which correspond to different ones of the output lines. When the resultant light beams from the coupling device illuminate the holographic plate, the spatial phase modulated pattern of optical beams selct and reconstruct a uniquely related one of the holograms on the holographic plate to enable transmission of intelligence carried by the optical beams through the reconstructed one of the holograms so as to be directed to the appropriate one of the light to electrical converting diodes to provide the connection to the associated one of the outgoing telephone lines thereby establishing a connection in the switching system from the active one of the incoming telephone lines to the selected one of the outgoing telephone lines.

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Midland Park, NJ, United States of America

Peter D Steensma